The present invention relates to a projection type display apparatus for enabling image display, by projecting an image on a image display element(s), enlargedly, upon a nearly vertical surface, and also for enabling image display upon a nearly horizontal surface, such as, a desk, etc.
As is described in Japanese Patent Laying-Open No. Hei 5-134213 (1993), there is already known a projection type image display apparatus for projecting an image upon a screen, enlargedly, in an oblique direction thereto, while shifting the projection image or picture into the vertical direction with respect to an optical axis of the projection optic system, with using an additional optic system, which is inclined to the optical axis of the projection optic system by a predetermined angle. However, the additional optic system mentioned herein (i.e., an afocual converter) is an optic system having a function of converting the size of the projection image or picture, and it is for obtaining a rectangular projection image with compensating/reducing distortions on the projection screen, which are generated accompanying with the projection from the direction oblique to the screen.    [Patent Document 1] Japanese Patent Laying-Open No. Hei 5-134213 (1993)
Within almost manners of using the conventional projection type display apparatus, as is shown in FIG. 13, while providing a screen (not shown in the figure) on the nearly vertical surface, such as, a wall surface 19, etc., the projection type display apparatus 101 is disposed on a base 20 or the like away from the wall surface 19, thereby projecting a projection image or picture on said screen. Hereinafter, such condition of providing the projection type display apparatus 101, as is shown in FIG. 13, is called “nearly horizontal disposition”.
In addition to the condition of use thereof as was motioned above, in recent years is increasing a demand of projecting the image or picture on the nearly horizontal surface, such as, a table or the like.
FIGS. 12(a) and 12(b) are views for showing the condition of projecting the image upon the nearly horizontal surface, such as, the table 14, etc., with using the conventional projection type image display apparatus 101. As is shown in FIG. 12(a), the conventional projection type image display apparatus 101 is fixed on a ceiling 15 by means of a fixing member 16, so that the projection is directed downwardly, and thereby displaying the projection image 5 on the table 14. Thus, the projection type image display apparatus 101 must be fixed on the ceiling. However, it should not be limited only to the way or manner of use, i.e., projecting upon the nearly horizontal surface, such as, the table, etc., for example, as is shown in FIG. 12(a). Of course, there is also other way of use, i.e., projecting upon the nearly vertical surface, such as, the wall surface, etc., as was shown in FIG. 13. Accordingly, there is generated a work of attaching/detaching of the projection type display apparatus 101 onto/from the ceiling 15; therefore being inferior in the usability thereof.
Also, there is other way of projection the image upon the table 14 while bending an optical path of projection; i.e., as is shown in FIG. 12(b), the projection type display apparatus 101 is disposed on the table 14, so as to project upward, while disposing a reflection mirror on the way of the optical path of projection thereof (being fixed on the table 14 by means of the fixing member 18). In case of this method, since there is no necessity for the projection type display apparatus 101 to be fixed, and also since it is on the table 14, it is possible to project the image upon the nearly vertical surface, such as, the wall surface, etc., as is shown in FIG. 13, easily, only by disposing the projection type display apparatus 101 with changing the projection direction thereof. Hereinafter, such condition of disposing the projection type display apparatus, as shown in FIGS. 12(a) and 12(b), is called “nearly vertical disposition”.